This invention relates to a leveling valve for controlling the amount of air within an air spring mounted between two members at least one of which is movable relative to the other. The leveling valve of this invention controls the air pressure in the air spring in response to changes in the distance between two such members. This leveling valve has its greatest use in maintaining a constant level of a vehicle chassis or frame relative to its axles in response to the loading and unloading of the vehicle.
Leveling valves per se are not new and have been used in the vehicle industry for a number of years such as disclosed in the U.S. Pat. Nos. to Schwartz U.S. Pat. No. 2,942,623, Valentine U.S. Pat. No. 3,071,393, and Barzelay U.S. Pat. No. 4,886,092. Prior art leveling valves have had several problems and disadvantages. One of these problems is an over-travel problem resulting from the mechanism which actuates the valve in response to changes in distance between two members. Yet another problem is the lack of any dampening device built into the leveling valve. Frequently, such dampening devices are units separated from the leveling valve itself. In those attempts to incorporate a dampening device in the valve, the mechanism has been extremely complicated as evidenced by U.S. Pat. No. 2,942,623 issued to Schwartz. Another problem is the lack of any limit to the valve part movement thus creating excessive seal wear in the valve. An additional problem is small passages or orifices in the valve as dictated by previous designs.
To my knowledge, there have been no effective dump features built into a leveling valve which can override the valve mechanism that controls the valve in response to the changes in the distance between two members. Prior devices also have been extremely complicated and expensive because of the large number of parts and the machining required on those parts. In addition, assembly costs of most leveling valves have been excessive resulting in a high cost to produce the valves.